Stochastic de sitter (inflationary) stage in the early universe

1988 ◽  
pp. 107-126 ◽  
Author(s):  
A. A. Starobinsky
Keyword(s):  
Early Universe ◽  
De Sitter

scholarly journals Schwinger effect in 4D de Sitter space and constraints on magnetogenesis in the early universe

2014 ◽  
Vol 2014 (10) ◽  
Author(s):  
Takeshi Kobayashi ◽  
Niayesh Afshordi
Keyword(s):  
Early Universe ◽  
De Sitter Space ◽  
De Sitter ◽  
Schwinger Effect

scholarly journals Formation of Conserved Charge at the de Sitter Space

Particles ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 355-363
Author(s):  
Valery V. Nikulin ◽  
Polina M. Petriakova ◽  
Sergey G. Rubin
Keyword(s):  
Early Universe ◽  
Extra Dimensions ◽  
De Sitter Space ◽  
Lepton Number ◽  
Relaxation Processes ◽  
Two Dimensional ◽  
Charge Accumulation ◽  
De Sitter ◽  
Extra Space

The article considers a new mechanism of charge accumulation in the early Universe in theories with compact extra dimensions. The relaxation processes in the extra space metric that take place during its formation lead to the establishment of symmetrical extra space configuration. As a result, the initial accumulation of the number associated with the symmetry occurs. We demonstrate this mechanism using a simple example of a two-dimensional apple-like extra space metric with U ( 1 ) -symmetry. The conceptual idea of the mechanism can be used to develop a model for the production of the baryon or lepton number in the early Universe.

A Finite Temperature λϕ 4 Model and De Sitter-Friedmann Phase Transition in the Early Universe

1982 ◽  
Vol 1 (2) ◽  
pp. 237-243 ◽  
Author(s):  
Guo Han-ying ◽  
Zou Zhen-long
Keyword(s):  
Phase Transition ◽  
Early Universe ◽  
Finite Temperature ◽  
De Sitter

scholarly journals A stringy perspective on the coincidence problem

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Francesc Cunillera ◽  
Antonio Padilla
Keyword(s):  
Phase Transition ◽  
Dark Energy ◽  
Early Universe ◽  
Low Energy ◽  
De Sitter ◽  
Coincidence Problem ◽  
String Compactifications ◽  
Slow Roll ◽  
De Sitter Vacua ◽  
Quintessence Field

Abstract We argue that, for string compactifications broadly consistent with swampland constraints, dark energy is likely to signal the beginning of the end of our universe as we know it, perhaps even through decompactification, with possible implications for the cosmological coincidence problem. Thanks to the scarcity (absence?) of stable de Sitter vacua, dark energy in string theory is assumed to take the form of a quintessence field in slow roll. As it rolls, a tower of heavy states will generically descend, triggering an apocalyptic phase transition in the low energy cosmological dynamics after at most a few hundred Hubble times. As a result, dark energy domination cannot continue indefinitely and there is at least a percentage chance that we find ourselves in the first Hubble epoch. We use a toy model of quintessence coupled to a tower of heavy states to explicitly demonstrate the breakdown in the cosmological dynamics as the tower becomes light. This occurs through a large number of corresponding particles being produced after a certain time, overwhelming quintessence. We also discuss some implications for early universe inflation.

scholarly journals INFLATIONARY DARK ENERGY FROM A CONDENSATE OF SPINORS IN A 5D VACUUM

2013 ◽  
Vol 22 (12) ◽  
pp. 1342028 ◽  
Author(s):  
PABLO ALEJANDRO SÁNCHEZ ◽  
MAURICIO BELLINI
Keyword(s):  
Dark Energy ◽  
Early Universe ◽  
Inflationary Universe ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Physical Origin ◽  
Sitter Spacetime ◽  
Interesting Candidate ◽  
Expansion Of The Universe ◽  
The Universe

What is the physical origin of dark energy? Could this energy be originated by other fields than the inflaton? In this paper, we explore the possibility that the expansion of the universe can be driven by a condensate of spinors. These spinors are free of interactions on five-dimensional (5D) relativistic vacuum in an extended de Sitter spacetime. The extra coordinate is considered as noncompact. After making a static foliation on the extra coordinate, we obtain an effective four-dimensional (4D) (inflationary) de Sitter expansion which describes an inflationary universe. In view of our results, we conclude that the condensate of spinors here studied could be an interesting candidate to explain the presence of dark energy in the early universe.

Dynamics of the Quasi-de Sitter Model of the Early Universe

2018 ◽  
Vol 81 (6) ◽  
pp. 894-898
Author(s):  
A. S. Kotanjyan ◽  
R. M. Avagyan ◽  
G. H. Harutunyan ◽  
N. A. Saharyan
Keyword(s):  
Early Universe ◽  
De Sitter ◽  
Sitter Model ◽  
De Sitter Model

scholarly journals Fermion production by a dependent of time electric field in de Sitter universe

2017 ◽  
Vol 32 (36) ◽  
pp. 1750208 ◽  
Author(s):  
Mihaela-Andreea Băloi ◽  
Cosmin Crucean
Keyword(s):  
Electric Field ◽  
Pair Production ◽  
External Electric Field ◽  
Early Universe ◽  
Total Probability ◽  
De Sitter ◽  
Expansion Factor ◽  
Gravitational Fields ◽  
De Sitter Universe ◽  
Strong Gravitational Fields

Fermion production in external electric field on de Sitter expanding universe is analyzed. The amplitude and probability of pair production are computed. We obtain from our calculations that the modulus of the momentum is no longer conserved. The rate of pair production in an electric field is found to be important in the early universe when the expansion factor was large comparatively with the particle mass. A computation of the total probability is presented in a particular case and the result proves to be nonvanishing only in strong gravitational fields.

A finite temperature λφ4 model and A De Sitter — Friedmann transition in the early universe

1982 ◽  
Vol 6 (3) ◽  
pp. 243-247
Author(s):  
Guo Han-ying ◽  
Zou Zhen-long
Keyword(s):  
Early Universe ◽  
Finite Temperature ◽  
De Sitter

COSMOLOGY WITH ADIABATIC MATTER CREATION

1994 ◽  
Vol 03 (01) ◽  
pp. 327-330 ◽  
Author(s):  
WINFRIED ZIMDAHL ◽  
DIEGO PAVÓN
Keyword(s):  
Stability Analysis ◽  
Energy Density ◽  
Early Universe ◽  
Particle Production ◽  
De Sitter ◽  
Matter Creation ◽  
Production Processes ◽  
Density Perturbations ◽  
Creation Rate

The standard Friedmann-Lemaître-Robertson-Walker (FLRW) model is modified to include particle production processes. The influence of these processes on the dynamics of the early Universe is investigated. We argue that a sufficiently high creation rate may give rise to an inflationary period. A stability analysis about this background yields growing energy density perturbations during the de Sitter stage.

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